In general, a magnetic field sensor based on a MEMS capacitive sensing technique includes a driving electrode movable in response to a magnetic field and a fixed electrode able to sense a capacitive variation corresponding to the movement of the driving electrode.
According to the magnetic field sensor principle, when reference current flows into the driving electrode in a predetermined direction, the driving electrode moves in a positive or negative direction to the fixed electrode due to Lorentz force according to the direction and intensity of magnetic field introduced from an outside.
In this case, a distance between both electrodes and an overlapped area of both electrodes are changed so that capacitance is changed. Thus, by detecting the variation in capacitance or a signal varying corresponding to the variation in capacitance, the magnetic field is sensed.
However, since Lorentz force utilized to sense a magnetic field is very small relative to gravity, there is a limitation on designing a structure of a sensor such as a spring, so that it is difficult to obtain a sufficient mechanical displacement.
In addition, when a signal, which is varied while AC or DC current is applied to the driving electrode for driving, is detected, it is not easy to detect a desired signal due to a mixing of currents